Buggy code:
public class Javadoc extends Task { public class DocletParam { private String name ; private String value ; public void setName ( String name ) { } public String getName ( ) { } public void setValue ( String value ) { } public String getValue ( ) { } } public static class ExtensionInfo extends ProjectComponent { private String name ; private Path path ; public void setName ( String name ) { } public String getName ( ) { } public void setPath ( Path path ) { } public Path getPath ( ) { } public Path createPath ( ) { } public void setPathRef ( Reference r ) { } } public class DocletInfo extends Javadoc . ExtensionInfo { private Vector params = new Vector ( ) ; public Javadoc . DocletParam createParam ( ) { } public Enumeration getParams ( ) { } } public static class PackageName { private String name ; public void setName ( String name ) { } public String getName ( ) { } public String toString ( ) { } } public static class SourceFile { private File file ; public SourceFile ( ) { } public SourceFile ( File file ) { } public void setFile ( File file ) { } public File getFile ( ) { } } public static class Html { private StringBuffer text = new StringBuffer ( ) ; public void addText ( String t ) { } public String getText ( ) { <START_BUG> return text . toString ( ) ; <END_BUG> } } public static class AccessType extends EnumeratedAttribute { public String [ ] getValues ( ) { } } private Commandline cmd = new Commandline ( ) ; private static boolean javadoc1 = JavaEnvUtils . isJavaVersion ( JAVA_1_1 ) ; private static boolean javadoc4 = ( ( ! ( JavaEnvUtils . isJavaVersion ( JAVA_1_1 ) ) ) && ( ! ( JavaEnvUtils . isJavaVersion ( JAVA_1_2 ) ) ) ) && ( ! ( JavaEnvUtils . isJavaVersion ( JAVA_1_3 ) ) ) ; private void addArgIf ( boolean b , String arg ) { } private void add12ArgIfNotEmpty ( String key , String value ) { } private void add12ArgIf ( boolean b , String arg ) { } private boolean failOnError = false ; private Path sourcePath = null ; private File destDir = null ; private Vector sourceFiles = new Vector ( ) ; private Vector packageNames = new Vector ( 5 ) ; private Vector excludePackageNames = new Vector ( 1 ) ; private boolean author = true ; private boolean version = true ; private Javadoc . DocletInfo doclet = null ; private Path classpath = null ; private Path bootclasspath = null ; private String group = null ; private String packageList = null ; private Vector links = new Vector ( 2 ) ; private Vector groups = new Vector ( 2 ) ; private Vector tags = new Vector ( 5 ) ; private boolean useDefaultExcludes = true ; private Javadoc . Html doctitle = null ; private Javadoc . Html header = null ; private Javadoc . Html footer = null ; private Javadoc . Html bottom = null ; private boolean useExternalFile = false ; private FileUtils fileUtils = FileUtils . newFileUtils ( ) ; private String source = null ; private Vector fileSets = new Vector ( ) ; private Vector packageSets = new Vector ( ) ; public void setUseExternalFile ( boolean b ) { } public void setDefaultexcludes ( boolean useDefaultExcludes ) { } public void setMaxmemory ( String max ) { } public void setAdditionalparam ( String add ) { } public void setSourcepath ( Path src ) { } public Path createSourcepath ( ) { } public void setSourcepathRef ( Reference r ) { } public void setDestdir ( File dir ) { } public void setSourcefiles ( String src ) { } public void addSource ( Javadoc . SourceFile sf ) { } public void setPackagenames ( String packages ) { } public void addPackage ( Javadoc . PackageName pn ) { } public void setExcludePackageNames ( String packages ) { } public void addExcludePackage ( Javadoc . PackageName pn ) { } public void setOverview ( File f ) { } public void setPublic ( boolean b ) { } public void setProtected ( boolean b ) { } public void setPackage ( boolean b ) { } public void setPrivate ( boolean b ) { } public void setAccess ( Javadoc . AccessType at ) { } public void setDoclet ( String docletName ) { } public void setDocletPath ( Path docletPath ) { } public void setDocletPathRef ( Reference r ) { } public Javadoc . DocletInfo createDoclet ( ) { } public void addTaglet ( Javadoc . ExtensionInfo tagletInfo ) { } public void setOld ( boolean b ) { } public void setClasspath ( Path path ) { } public Path createClasspath ( ) { } public void setClasspathRef ( Reference r ) { } public void setBootclasspath ( Path path ) { } public Path createBootclasspath ( ) { } public void setBootClasspathRef ( Reference r ) { } public void setExtdirs ( String path ) { } public void setExtdirs ( Path path ) { } public void setVerbose ( boolean b ) { } public void setLocale ( String locale ) { } public void setEncoding ( String enc ) { } public void setVersion ( boolean b ) { } public void setUse ( boolean b ) { } public void setAuthor ( boolean b ) { } public void setSplitindex ( boolean b ) { } public void setWindowtitle ( String title ) { } public void setDoctitle ( String doctitle ) { } public void addDoctitle ( Javadoc . Html text ) { } public void setHeader ( String header ) { } public void addHeader ( Javadoc . Html text ) { }

Fix:
return text . substring ( 0 ) ;